Any blender GUI toolkit for use with Game engine?
There is a library called bgui that makes creating GUI for the bge much easier. 

There are two locations for the documentation, the old (but better) google project wiki and the read the docs page.

In a nutshell, add the bgui script to your project with a python controller in the logic editor. Use a always sensor to trigger the script to always run.

Next you add widgets or components to bgui with a line such as this (this will add a button).

# A FrameButton widget
self.btn = bgui.FrameButton(self.frame, 'button', text='Click Me!', size=[0.3, 0.1], pos=[0, 0.4], options=bgui.BGUI_DEFAULT | bgui.BGUI_CENTERX)